1. Field of the Invention
This invention relates to a building block construction for use in the building and construction industry, as well as for use in educational, developmental or toy construction sets, and more particularly relates to an interlocking tetrahedral block design which, when interfitted with other similar blocks provides a structural system suitable for load bearing applications.
2. Description of the Prior Art
A geometric structure formed of a plurality of tetrahedrally shaped tensegrity modules is disclosed in U.S. Pat. No. 4,207,715 (Fuller). The modules are described in the Fuller patent as being formed from a series of compression members, or struts, joined together at a center point, and a number of tension elements joined to the ends of the compression members. The compression numbers define four equilateral triangular faces on the module, and form the edges of each triangular face. Each module may be covered by a skin or membrane to define a closed outer surface.
As shown in FIG. 8 of the Fuller patent, the tetrahedral modules may be arranged so that their triangular faces abut and overlap (with the vertices of the abutting triangular faces in nonalignment) to form a continuous overlapping arrangement which defines and encircles a pyramidal dimple.
The tetrahedral modules disclosed in the Fuller patent may be arranged to form a variety of geometric structures. However, these structures relay on tension forces to maintain their form, that is, the tension forces exerted by each module on its adjacent module contribute to the tensile integrity of the whole structure. The structure must be assembled as a whole, and supported during assembly, and then placed under tension to maintain structural integrity.
Because each module is not "self-supporting" and an external scaffolding is needed to support the module assembly during its construction, the applicability of the module of block construction disclosed in the Fuller patent is limited.